JP2000235165A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and lightweight video display device constituted so that a video displayed at one display element is given to a left and a right eyes. SOLUTION: A half mirror 11 is arranged by being inclined by 45 deg. with respect to an LCD 10 and a mirror 12 is arranged on the optical path of light transmitted through the mirror 11 in parallel with the LCD 10. A half mirror 13 is arranged on the optical path of light reflected on the mirror 11 by being inclined by 45 deg. with respect to the optical path and a mirror 14 is arranged on the optical path of light transmitted through the mirror 13 vertically to the optical path. A half mirror 15 is arranged on the optical path of the reflected light of the mirror 12 reflected on the mirror 11 in parallel with the mirror 13. Then, the light is guided to eyepieces 16 and 17 from the mirrors 13 and 15. By making a distance to the mirrors 13 and 15 from the mirror 11 equal to a distance to the mirror 14 from the mirror 13, the length of the left and the right optical paths is made identical.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device which is used in front of an observer's eyes, and more particularly to an image display for providing an image displayed on one display element to both eyes of the observer. Related to the device.

[0002]

2. Description of the Related Art There is an image display device mounted on a head or held by a hand and used in front of an observer's eyes.
Such an image display device is configured so that the displayed image is enlarged by the left and right eyepiece optical systems and guided to both eyes of the observer, and can provide an image with a wide field of view. A configuration in which two display elements for displaying video are provided to individually display video provided to the left and right eyes, and a configuration in which only one display element is provided and the video light is divided and guided to the left and right eyes The configuration is common.

In an apparatus having two display elements, the configuration of an optical system for guiding the light of the display element to the eyes of an observer can be made the same on the left and right sides, and the design is easy. However, since two expensive display elements are provided, the device itself becomes expensive.
Further, since the display element is relatively heavy and it is necessary to provide two light sources for illuminating the display element, it is difficult to reduce the weight of the device.

On the other hand, in an apparatus having only one display element and dividing the image light into two, the cost can be reduced. On the other hand, images to be provided to the left and right eyes must have the same orientation, the same size, and the same brightness, and the configuration of an optical system for guiding the split light to the left and right eyes becomes complicated.

[0005] Japanese Patent Application Laid-Open No. 7-64015 proposes a device for dividing the image light of a display element into two by a half mirror. The display element is in front of the center of the left and right eyepieces,
The half mirror is disposed perpendicular to the optical axis of the eyepiece, and the half mirror is disposed at an angle of 45 ° with respect to the display element. The reflected light of the half mirror is guided to one eyepiece by one total reflection mirror, and the transmitted light is guided to the other eyepiece by two total reflection mirrors. In order to equalize the size and brightness of the image on the left and right, the optical path length of the light after division is set to be equal, but this increases the optical path length in the optical axis direction of the eyepiece, and makes the device thicker. I have.

US Pat. No. 5,245,472 discloses an apparatus for splitting image light of a display element into two by a cross prism having two translucent reflective films orthogonal to each other. The display element is arranged in front of the center of the left and right eyepieces, perpendicular to the optical axis of the eyepiece, and the cross prism is arranged with two reflection films inclined at 45 ° to the display element. The two reflected lights by the cross prism are respectively guided to the eyepiece by the total reflection mirror. In this configuration,
Although the optical path length is shorter and the device is smaller than the above device, the weight is greatly increased by using a prism. Further, since the cross prism is expensive, the meaning of having one display element is reduced by half.

Japanese Patent Application Laid-Open No. 7-110455 discloses that a display element is arranged on one side of an apparatus in parallel with an optical axis of an eyepiece, and a half mirror is provided in front of an eyepiece closer to the display element. A configuration in which a total reflection mirror is arranged in front of one eyepiece is shown. The image light of the display element is split into reflected light and transmitted light by a half mirror, and the reflected light is directly guided to one eyepiece, and the transmitted light is guided to the other eyepiece by a total reflection mirror. A lens for correcting a difference in optical path length is provided between the half mirror and the total reflection mirror. In this configuration, since a correcting lens exists only in one optical path, a special design is required to make the imaging performance uniform. In addition, the weight of the apparatus is increased by the amount of the correction lens, and the weight balance is not good because the display element is on one side.

Although it is not a configuration for splitting the light of the display element,
Japanese Patent Application Laid-Open No. Hei 6-315125 discloses a device for extracting image light from both front and back surfaces of a transmission type display element. The display elements are arranged in front of the center of the left and right eyepieces in parallel with the optical axis of the eyepieces, and half mirrors for guiding light from the display elements are arranged in front of the left and right eyepieces. Further, light sources for illuminating the display element via half mirrors are provided on both sides of the device.
The display elements alternately display images in opposite directions, and the illumination is switched in synchronization with the display. In this configuration, the left and right optical systems can be the same, but the device is heavy because it has two light sources for illuminating the display element. Also,
It is necessary to switch between display and illumination in synchronization, which complicates the control.

[0009]

It is strongly demanded that an image display device mounted on a head or held by hand during use be small and lightweight. In addition, since the device is for personal use, it is desirable that the price be as low as possible.
However, as described above, a video display device having only one display element has a feature of being inexpensive,
The optical system is complicated, and both miniaturization and weight reduction cannot be achieved sufficiently.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a small and lightweight image display device that provides an image displayed on one display element to left and right eyes.

[0011]

In order to achieve the above object, the present invention has a display element for displaying an image, and is disposed in front of the observer so that the light of the image on the display element is transmitted to both observers. In an image display device for guiding to an eye, first to fifth reflecting elements and first and second eyepiece optical systems are provided in the following positional relationship.

The first reflecting element is semi-transmissive, and is disposed on the optical path of light from the display element at an angle of 45 ° with respect to the display surface of the display element. The second reflective element is disposed on the optical path of light from the display element that has passed through the first reflective element and is parallel to the display surface of the display element. The third reflective element is semi-transmissive, and is disposed on the optical path of light from the display element reflected by the first reflective element at an angle of 45 ° with respect to this optical path. The fourth reflecting element is the first reflecting element that has passed through the third reflecting element.
Is arranged on the optical path of the light from the reflective element perpendicular to the optical path. The fifth reflecting element is provided on the optical path of the light from the second reflecting element reflected by the first reflecting element.
Are arranged in parallel to the reflection element.

The first eyepiece optical system is arranged on the optical path of light from the fourth reflecting element reflected by the third reflecting element. The second eyepiece optical system is disposed on an optical path of light from the first reflecting element reflected by the fifth reflecting element.

Further, the distance from the first reflecting element to the third reflecting element is equal to the distance from the first reflecting element to the fifth reflecting element, and the distance from the first reflecting element to the second reflecting element is made equal. The distance to the element is made equal to the distance from the third reflective element to the fourth reflective element.

In this image display device, the arrangement positions of the components other than the fourth reflection element are symmetric. In use, the first
Eyepiece optics and a third reflective element in front of one eye,
The eyepiece optical system and the fifth reflection element are located in front of the other eye, and the display element, the first reflection element, and the second reflection element are located at the left and right centers in front of the observer's face. Of the five reflective elements, at least the first and third reflective elements are translucent.

The light of the image displayed by the display element is first
Incident on the reflection element of the first and second reflected light and transmitted light.
Divided. The light reflected by the first reflecting element is incident on a semi-transmissive third reflecting element, passes through the third reflecting element, and is reflected by the fourth reflecting element. This light is incident again on the third reflecting element, is reflected and is incident on the first eyepiece optical system.
On the other hand, the light transmitted through the first reflecting element is reflected by the second reflecting element, re-enters the first reflecting element, and is reflected. This light enters the fifth reflecting element, is reflected and enters the second eyepiece optical system.

Here, the optical path length until the light reflected by the first reflecting element enters the first eyepiece optical system, and the light transmitted through the first reflecting element enters the second eyepiece optical system. The optical path length up to this point is equalized by the above setting. For this reason, it is not necessary to arrange another optical element to correct the optical path length. In addition, since the five reflection elements are not present at the same position, it is possible to adopt a configuration in which a reflection film is formed on a flat plate. Therefore, the image display device is light in weight. In addition, since the arrangement positions of the components are close to symmetry, and only one asymmetric fourth reflecting element is lightweight, the weight balance of the device is good.

[0018] The first reflecting element is provided with the light from the display element and the second reflecting element.
Is reflected in a direction orthogonal to the optical axes of the first and second eyepiece optical systems. This is because the display element, the first reflective element, and the second
Regardless of the angle of the reflective element. For example,
The display element and the second reflection element may be arranged perpendicular to the optical axis of the eyepiece optical system, and the first reflection element may be inclined at 45 ° with respect to the optical axis of the eyepiece optical system. And the second reflecting element are arranged in parallel to the optical axis of the eyepiece optical system,
The first reflecting element may be parallel to the optical axis of the eyepiece optical system. The display element, the first reflection element, and the second reflection element are arranged in the front-rear direction in the former setting, and are arranged in the up-down direction in the latter setting.

The display element can be arranged close to the first reflection element, and the second and fourth reflection elements can be arranged close to the first and third reflection elements, respectively. It is. Therefore, the video display device, before and after,
It can be configured small in all directions, up, down, left, and right.

The reflectance of the semi-transmissive first and third reflective elements is set so that the amounts of light incident on the first and second eyepiece optical systems are equal. In addition, the fifth reflective element also sets the reflectance as semi-transmissive as necessary so that the amounts of light incident on the first and second eyepiece optical systems are equal. The second reflective element and the fourth reflective element may be totally reflective or semi-transmissive, but are preferably totally reflective to eliminate loss of light.

In the image display device having the above structure, each of the first reflection element and the third reflection element is constituted by a polarization separation film which transmits one of two polarization components whose polarization planes are perpendicular to each other and reflects the other. , A quarter-wave plate may be provided between each of the first and second reflection elements and between the third and fourth reflection elements.

The first reflection element divides light having a disordered plane of polarization incident from the display element into two polarization components. The third reflective element can be set to transmit light reflected by the first reflective element. At this time, the first
Is reflected by the third reflecting element, is reflected by the fourth reflecting element, and is incident on the third reflecting element again as described above. During this time the light is 1 /
The light is transmitted twice through the four-wavelength plate, and its polarization plane is 90
゜ Rotate. Therefore, the light that has reentered the third reflecting element is reflected and enters the first eyepiece optical system.

The light transmitted through the first reflecting element is also transmitted through the quarter-wave plate twice before being reflected by the second reflecting element and re-entering the first reflecting element. The plane rotates 90 °. Therefore, light that has reentered the first reflecting element is reflected, further reflected by the fifth reflecting element, and enters the second eyepiece optical system.

In this configuration, half of the light from the display element can be guided to one eye and the other can be guided to the other eye, and the light use efficiency can be increased.

A lens for increasing the viewing angle may be provided between the first and third reflecting elements and between the first and fifth reflecting elements. It is possible to provide an image with a large viewing angle without increasing the magnification of the eyepiece optical system so much.
In addition, the size of the fifth reflecting element can be reduced. Moreover, the distance from the first reflecting element to the third reflecting element and the fifth reflecting element is defined by the distance between the left and right eyes, and even if a lens is arranged on these optical paths, the third reflecting element and the 5 does not affect the position of the reflection element. Therefore, the size of the image display device can be further reduced.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the video display device of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the video display device 1 according to the first embodiment. The image display device 1 includes a liquid crystal display (LCD) 10 as a display element,
Three half mirrors 11 and 13 as five reflecting elements,
15 and two total reflection mirrors 12 and 14 and eyepieces 16 and 17 as two eyepiece optical systems.

The LCD 10 is of a transmissive type, and a display surface is vertically illuminated with light from a light source arranged outside the figure. The half mirrors 11, 13, 15 and the total reflection mirrors 12, 14
Each is formed by providing a reflective film on the surface of a thin flat plate. The half mirrors 13 and 15 have the same size.

The half mirror 11 is located between the LCD 10 and the total reflection mirror 12. The half mirror 11 and the total reflection mirror 12 are arranged so that a straight line L1 passing through the center of the display surface of the LCD 10 and perpendicular to the display surface passes through the respective centers. The half mirror 11 is arranged at an angle of 45 ° with respect to the display surface of the LCD 10, and the total reflection mirror 12 is arranged parallel to the display surface of the LCD 10.

The half mirror 13 and the half mirror 15
With the half mirror 11 interposed, straight lines L2 orthogonal to the straight line L1 on the half mirror 11 are arranged so as to pass through their respective centers. Half mirror 13 and half mirror 1
5 are arranged at an angle of 45 ° to the straight line L2 and parallel to each other. Half mirror 13 is half mirror 11
And the total reflection mirror 14. Total reflection mirror 14
Are arranged such that the straight line L2 passes through the center. The total reflection mirror 14 is arranged perpendicular to the straight line L2, and is also perpendicular to the LCD 10 and the total reflection mirror 12.

The eyepiece 16 is arranged at an angle of 45 ° with respect to the half mirror 13 so that its optical axis is orthogonal to the straight line L 2 on the half mirror 13. The eyepiece 17 also has a light axis L2 on the half mirror 15
The optical axis with respect to the half mirror 15 by 4
It is arranged at an angle of 5 °. The eyepieces 16 and 17 are
The optical axes are parallel to each other and are on the same side with respect to the straight line L2.

The distance from the center of the half mirror 11 to the center of the half mirror 13 is equal to the distance from the center of the half mirror 11 to the center of the half mirror 15, and is の of the distance between the observer's eyes E1, E2. Is set to Therefore, at the time of use, the half mirrors 13 and 15 are located in front of both eyes of the observer, and the LCD 10, the half mirror 11 and the total reflection mirror 12 are located in the left and right center in front of the face.

The distance from the center of the half mirror 11 to the center of the total reflection mirror 12 and the distance from the center of the half mirror 13 to the center of the total reflection mirror 14 are set equal. Eyepiece 1 from center of half mirror 13
6 is set to be equal to the distance from the center of the half mirror 15 to the eyepiece 17.

In order to make the image display device 1 as small as possible, the display element 10 is arranged close to the half mirror 11, and the total reflection mirror 12 and the total reflection mirror 14
Are respectively a half mirror 11 and a half mirror 13
It is arranged close to.

The image light from the LCD 10 first enters the half mirror 11 and is split into two parts: reflected light and transmitted light. The light reflected by the half mirror 11 enters the half mirror 13 and is split into reflected light and transmitted light, and the reflected light is discarded. The light transmitted through the half mirror 13 is incident on the total reflection mirror 14 and is reflected, and is incident on the half mirror 13 again. This light is split into reflected light and transmitted light, and the transmitted light travels toward the half mirror 11. The light reflected by the half mirror 13 enters the eyepiece 16 and is guided to one eye E1 of the observer.

On the other hand, the LCD that has passed through the half mirror 11
The light from 10 enters the total reflection mirror 12 and is reflected, and then enters the half mirror 11 again. This light is split into reflected light and transmitted light, and the transmitted light is discarded. The light reflected by the half mirror 11 enters the half mirror 15 together with the light from the half mirror 13 transmitting through the half mirror 11. This light is split into reflected light and transmitted light, and the transmitted light is discarded.
The light reflected by the half mirror 15 is the eyepiece 1
7, and is guided to the other eye E2 of the observer.

The observer can see L through the eyepieces 16 and 17
You will see an enlarged virtual image of the display surface of CD10,
An image with a large viewing angle can be observed. Binocular E
1. The directions of the images observed at E2 are the same. Further, by setting the distance, the optical path length from the half mirror 11 to one eye E1 and the optical path length from the half mirror 11 to the other eye E2 are determined.
Are equal, and the size of the image is the same.

The amount of image light guided to both eyes E 1 and E 2 is determined by the reflectance of the half mirrors 11, 13 and 15.
The amount of image light of the LCD 10 is A0, and the amount of light guided to the eyes E1, E2 is A1, A2, the half mirrors 11, 13, respectively.
The reflectivity of No. 15 is represented by R1, R3 and R5, respectively. The light guided to the eye E1 passes through the reflection of the half mirror 11 and the transmission and reflection of the half mirror 13 in this order.
Is obtained by the following equation 1. The light guided to the eye E2 is transmitted and reflected by the half mirror 11, and reflected by the half mirror 15
And the reflection of the half mirror 11, the transmission of the half mirror 13 twice, the transmission of the half mirror 11, and the reflection of the half mirror 15 in this order. Is required.

A1 = A0 × R1 × (1-R3) × R3 Equation 1 A2 = A0 × (1-R1) × R1 × R5 + A0 × R1 × (1-R3) × (1-R3) × (1−R1) × R5 = A0 × R1 × (1-R1) × {1+ (1-R3) ² } × R5 Equation 2

In the image display device 1, in order to make the images observed by both eyes E1 and E2 the same brightness, A1 = A2.
The reflectances R1, R3, and R5 are set so as to satisfy the relationship of the following Expression 3. R3 × (1-R3) = (1-R1) × {1+ (1-R3) ² } × R5 Formula 3

For example, in the first setting, R1 = 0.5, R3
= 0.5, R5 = 0.4, R1 = 0.6 in the second setting,
R3 = 0.5, R5 = 0.5, and in the third setting, R1 = 0.
8, R3 = 0.5, R5 = 1, and in the fourth setting, R1 = 0.
825, R3 = 0.755, R5 = 1. Eyes E1, E2
Of the image light in the first setting.
5%, 15% for the second setting, 20% for the third setting,
The fourth setting is 15.3%. The third and fourth settings indicate that a total reflection mirror can be used instead of the half mirror 15.

The positional relationship described above includes a straight line L 1 passing through the center of the display surface of the LCD 10 and perpendicular to the display surface, and a half mirror 1.
A straight line L2 connecting the center of 3 and the center of the half mirror 15 is
The inclination of the straight line L2 and the inclination of the straight line L1 with respect to the plane including the optical axes of the eyepieces 16 and 17 may be set arbitrarily only by specifying that the line is orthogonal on the half mirror 11. That is, the straight line L1 can be parallel or perpendicular to the optical axes of the eyepieces 16 and 17, or can have another angular relationship.

In a configuration in which the straight line L1 is parallel to the optical axes of the eyepieces 16 and 17, the LCD 10 and the total reflection mirror 12 are arranged in the front-rear direction, and the half mirror 11 is positioned with respect to the optical axes of the eyepieces 16 and 17. Would be 45 °.
In a configuration in which the straight line L1 is perpendicular to the optical axes of the eyepieces 16 and 17, the LCD 10 and the total reflection mirror 12 are vertically arranged, and the half mirror 11 is
7 becomes parallel to the optical axis. Since the LCD 10 and the total reflection mirror 12 have a flat plate shape and are disposed close to the half mirror 11, the difference between the size of the image display device 1 in the front-rear direction and the size of the image display device 1 in the up-down direction is not limited. Rarely occurs.

In order to be able to cope with individual differences in the distance between the eyes E1 and E2, a set of a half mirror 13, a total reflection mirror 14 and an eyepiece 16 and a half mirror 15 and an eyepiece 17 A mechanism for changing the interval between the pair may be provided. The mechanism is set such that the distance from the half mirror 11 to the half mirror 13 and the distance from the half mirror 11 to the half mirror 15 are always equal.

In this case, an LCD which modulates light supplied from the outside and uses image light as a specific polarization component is used as a display element. However, like the half mirror of the present embodiment, the characteristic is that of incident light. When a semi-transmissive reflective element that does not depend on the polarization component is used, any type of display element can be used. For example, a field emission display (FED) or an electroluminescence display (ELD), which emits light by itself and in which video light contains a disordered polarization component, can be used. However, a display element having a large size and weight, such as a conventional cathode ray tube (CRT), is not preferable because it hinders reduction in size and weight of the image display device 1.

FIG. 2 shows the configuration of the video display device 2 according to the second embodiment. The image display device 2 has an FED as a display element.
20, 2 polarization splitters (PBS) as 5 reflective elements
Mirrors 21, 23 and three total reflection mirrors 22, 24, 2
5, eyepiece lenses 26 and 27 are provided as two eyepiece optical systems. Further, two quarter-wave plates 22a and 24a are provided.

The PBS mirrors 21 and 23 are formed by providing, on a thin flat plate surface, a PBS film that transmits one of two polarization components whose polarization planes are orthogonal to each other and reflects the other. FIG. 3 shows the effect of the PBS film on the incident light. In this example, the PBS film F transmits P-polarized light and S
It is set to reflect polarized light. Among the polarization components included in the incident light, the component whose polarization plane is parallel to the paper is PBS
A component which becomes P-polarized light with respect to the film F and transmits through the PBS film F, and a component whose polarization plane is perpendicular to the paper surface becomes S-polarized light with respect to the PBS film F and is reflected by the PBS film F.

The FED 20, the PBS mirror 21, and the total reflection mirror 22 are the same as those of the image display device 1 of the first embodiment.
They correspond to the CD 10, the half mirror 11, and the total reflection mirror 12, respectively, and their positional relationship is set to be the same as that of the video display device 1. The PBS mirror 23, the total reflection mirror 24, the total reflection mirror 25, the eyepiece 26, and the eyepiece 27 are provided by the half mirror 13, the total reflection mirror 14, and the half mirror 1 of the image display device 1.
5, the eyepiece 16 and the eyepiece 17, respectively, and their positional relationship is also shown in the image display device 1.
Is set to the same as

The distance from the center of the PBS mirror 21 to the center of the PBS mirror 23 is equal to the distance from the center of the PBS mirror 21 to the center of the total reflection mirror 25, and from the center of the PBS mirror 21 to the center of the total reflection mirror 22. Is equal to the distance from the center of the PBS mirror 23 to the center of the total reflection mirror 24, which is the same as the image display device 1.

The quarter-wave plate 22a is a PBS mirror 21
And the total reflection mirror 22 are arranged in parallel with the total reflection mirror 22. The quarter wave plate 24a is made of PBS
Between the mirror 23 and the total reflection mirror 24, the total reflection mirror 2
4 are arranged in parallel with each other.

A straight line L 1 passing through the center of the display surface of the FED 20 and perpendicular to the display surface is orthogonal to a straight line L 2 connecting the center of the PBS mirror 23 and the center of the total reflection mirror 25 on the PBS mirror 21 and the eyepiece lens 26. , 27 are set in parallel with the optical axis. Therefore, FED 20, 1
The 波長 wavelength plate 22a and the total reflection mirror 22 are arranged in the front-back direction. The PBS mirror 21 is set to reflect P-polarized light and transmit S-polarized light, and the PBS mirror 23 is set to reflect S-polarized light and transmit P-polarized light.

FIG. 4 shows the optical path of the image light from the FED 20 to the observer's eyes E1 and E2, and the polarization components on the optical path. The polarization plane of the light emitted from the FED 20 is disordered, and the image light includes a component that becomes P-polarized light and a component that becomes S-polarized light with respect to the PBS mirror 21. Of the light incident on the PBS mirror 21, P-polarized light is reflected and S-polarized light is transmitted.

The light reflected by the PBS mirror 21 enters the PBS mirror 23, but is reflected by the PBS mirror 23.
Are also P-polarized light, so that they are all transmitted. The light transmitted through the PBS mirror 23 is incident on and reflected by the total reflection mirror 24, and is incident again on the PBS mirror 23. During this time, the light passes through the quarter-wave plate 24a twice, and the polarization plane is rotated by 90 °. Therefore, the PBS mirror 23
Are re-incident as S-polarized light with respect to the PBS mirror 23 and are all reflected. The light reflected by the PBS mirror 23 enters the eyepiece lens 26 and is guided to one eye E1 of the observer.

On the other hand, the light transmitted through the PBS mirror 21 is
The incident light is reflected by the total reflection mirror 22 and is reflected by the PBS mirror 2.
Re-enter at 1. During this time, the light is transmitted twice through the quarter-wave plate 22a, and the polarization plane is rotated by 90 °. Therefore, the light re-entering the PBS mirror 21 is
The light becomes P-polarized light with respect to the mirror 21 and is all reflected.
The light reflected by the PBS mirror 21 is incident on the total reflection mirror 25, is reflected, is incident on the eyepiece 27, and is guided to the other eye E2 of the observer.

In the image display device 2, there is no light loss due to the PBS mirrors 21 and 23 which are semi-transmissive reflecting elements.
One half of the image light of the FED 20 is guided to both eyes E1 and E2. Therefore, a bright image can be provided.

The straight line L1 passing through the center of the display surface of the FED 20 and perpendicular to the display surface is oriented perpendicular to the optical axes of the eyepieces 26 and 27, and the FED 20, the quarter-wave plate 22a and the total reflection mirror 22 are They may be arranged vertically. In that case, the light reflected by the PBS mirror 21 is P
Since the S-polarized light is transmitted to the BS mirror 23, the PBS mirror 23 is set to transmit the S-polarized light and reflect the P-polarized light.

Here, the FED is used as the image display element.
Is used, but an ELD may be used. It is also possible to use an LCD provided with a scattering plate that makes the polarization plane of the image light random.

FIG. 5 shows the configuration of the video display device 3 according to the third embodiment. This image display device 3 is obtained by adding polarizing plates 26b and 27b to the image display device 2 of the second embodiment. The polarizing plate 26b is disposed between the PBS mirror 23 and the eyepiece 26 perpendicular to the optical axis of the eyepiece 26. The polarizing plate 27 b is disposed between the total reflection mirror 25 and the eyepiece 27, perpendicular to the optical axis of the eyepiece 27.

Even when a setting error occurs in the PBS mirrors 21 and 23 and the separation of two polarization components whose polarization planes are perpendicular becomes incomplete, unnecessary polarization components are removed from the polarization plates 26b and 27b.
, And an image of the same brightness without ghost can be provided to both eyes E1 and E2. The polarizing plates 26b and 27b are connected to the eyepieces 26 and 27 and the eye E1,
It may be arranged between E2.

FIG. 6 shows the configuration of the video display device 4 according to the fourth embodiment. The image display device 4 has an FED as a display element.
40, three PBS mirrors 41 as five reflecting elements,
43, 45, two total reflection mirrors 42, 44, and two total reflection concave mirrors 46, 47 as eyepiece optical systems. Also, four quarter-wave plates 42a, 44a, 46
a, 47a.

The FED 40, the PBS mirror 41, the total reflection mirror 42, and the quarter-wave plate 42a are the same as the FED 20, the PBS mirror 21, the total reflection mirror 22, and the quarter-wave plate 22a of the video display device 2 of the second embodiment. , And are set in the same positional relationship as the video display device 2. The PBS mirror 43, the total reflection mirror 44, and the quarter-wave plate 44a are the PBS mirror 23, the total reflection mirror 24, and the quarter-wave plate 24a of the image display device 2.
And the PBS mirror 43 is 9
The positional relationship is set the same as that of the video display device 2 except that the video display device 2 is arranged to be rotated by 0 °. PBS mirror 4
Numeral 5 corresponds to the total reflection mirror 25 of the image display device 2, but is arranged by rotating by 90 °.

The distance from the center of the PBS mirror 41 to the center of the PBS mirror 43 is equal to the distance from the center of the PBS mirror 41 to the center of the PBS mirror 45, and the distance from the center of the PBS mirror 41 to the center of the total reflection mirror 42. The distance is equal to the distance from the center of the PBS mirror 43 to the center of the total reflection mirror 44.

The concave mirror 46 has an optical axis of the PBS mirror 4.
P is a straight line L2 connecting the center of 3 and the center of the PBS mirror 45.
They are arranged orthogonally on the BS mirror 43. The concave mirror 47 is disposed so that the optical axis is orthogonal to the straight line L2 on the PBS mirror 45. Concave mirrors 46, 4
7, the optical axis is parallel, and the distance from the center of the PBS mirror 43 to the center of the concave mirror 46 is equal to the distance from the center of the PBS mirror 45 to the center of the concave mirror 47.

The 波長 wavelength plate 46 a is disposed between the PBS mirror 43 and the concave mirror 46, perpendicular to the optical axis of the concave mirror 46. The 波長 wavelength plate 47 a is arranged between the PBS mirror 45 and the concave mirror 47 so as to be perpendicular to the optical axis of the concave mirror 47.

A straight line L 1 passing through the center of the display surface of the FED 40 and perpendicular to the display surface is set parallel to the optical axes of the concave mirrors 46 and 47. That is, the FED 40, the total reflection mirror 42, and the quarter-wave plate 42a are arranged in the front-back direction. Similarly to the image display device 2, the PBS mirror 41 is set to reflect P-polarized light and transmit S-polarized light, and the PBS mirror 43 is set to reflect S-polarized light and transmit P-polarized light. The PBS mirror 45 is set to reflect P-polarized light and transmit S-polarized light.

FIG. 7 shows the optical path of the image light from the FED 40 to the observer's eyes E1 and E2, and the polarization components on the optical path. Of the image light from the FED 40, the PBS mirror 41
The component that becomes P-polarized light is reflected, and the component that becomes S-polarized light is transmitted.

The light reflected by the PBS mirror 41 is incident on the PBS mirror 43 as P-polarized light, and is entirely transmitted. The light transmitted through the PBS mirror 43 enters the total reflection mirror 44 and is reflected. During this time, the light passes through the quarter-wave plate 44a twice, whereby the polarization plane is rotated by 90 °. This light enters the PBS mirror 43 again as S-polarized light, and is all reflected. The light reflected by the PBS mirror 43 is incident on the concave mirror 46, is reflected and converges, and is incident on the PBS mirror 43 again. During this time, the light is transmitted twice through the quarter-wave plate 46a, and the polarization plane is rotated by 90 °. Accordingly, the light is P-polarized light with respect to the PBS mirror 43, and all of the light passes through and enters the observer's eye E1.

On the other hand, the light transmitted through the PBS mirror 41 is
The light enters the total reflection mirror 42 and is reflected.
By transmitting twice through the wave plate 42a, the polarization plane becomes 90
゜ Rotate. This light enters the PBS mirror 41 as P-polarized light, and is all reflected. The light reflected by the PBS mirror 41 is also reflected on the PBS mirror 45 by P
It enters as polarized light and is all reflected. PBS mirror 45
The light reflected by the light enters the concave mirror 47 and is reflected and converges, and then re-enters the PBS mirror 45. During this time, the light is transmitted twice through the quarter-wave plate 47a, and the polarization plane is rotated by 90 °. Therefore, the light is S-polarized with respect to the PBS mirror 45, and all of the light passes through and enters the observer's eye E2.

The observer sees an enlarged virtual image on the display surface of the FED 40 via the concave mirrors 46 and 47, and can observe an image with a large viewing angle. By setting the above-described distance, one eye E is moved from the PBS mirror 41.
The optical path length to 1 and the optical path length from the PBS mirror 41 to the other eye E2 are equal, and the size of the image observed by both eyes E1 and E2 is the same.

In the image display device 4 as well, there is no light loss due to the PBS mirrors 41, 43 and 45, which are semi-transmissive reflective elements, and half of the image light of the
1, led to E2. Therefore, a bright image can be provided.

The straight line L1 passing through the center of the display surface of the FED 40 and perpendicular to the display surface is made perpendicular to the optical axes of the concave mirrors 46 and 47, and the FED 40, the quarter-wave plate 42a and the total reflection mirror 42 are They may be arranged vertically. In that case, the light reflected by the PBS mirror 41 is P
Since S-polarized light is applied to the BS mirrors 43 and 45, PB
The S mirror 43 is set to transmit S polarized light and reflects P polarized light, and the PBS mirror 45 is set to reflect S polarized light and transmit P polarized light.

FIG. 8 shows the configuration of the video display device 5 according to the fifth embodiment. The image display device 5 is obtained by adding polarizing plates 46b and 47b to the image display device 4 of the fourth embodiment. The polarizing plate 46b is arranged on the opposite side of the concave mirror 46 with respect to the PBS mirror 43, and perpendicular to the optical axis of the concave mirror 46. The polarizing plate 47b is a PBS mirror 4
On the opposite side of the concave mirror 47 with respect to 5, the concave mirror 47
Are arranged perpendicularly to the optical axis of. Polarizing plate 46b,
47b is located immediately before the eyes E1 and E2 of the observer and blocks unnecessary polarized light components.

FIG. 9 shows the configuration of the video display device 6 according to the sixth embodiment. This image display device 6 is different from the image display device 2 of the second embodiment in that lenses 28, 2
9 is added. The lens 28 is disposed between the PBS mirror 21 and the PBS mirror 23 so that the optical axis is aligned with a straight line L2 connecting the center of the PBS mirror 23 and the center of the total reflection mirror 25. The lens 29 is arranged between the PBS mirror 21 and the total reflection mirror 25 so that the optical axis coincides with the straight line L2.

The lenses 28 and 29 have the same size and the same power. The distance from the center of the PBS mirror 21 to the center of the lens 28 is twice as long as the distance from the center of the PBS mirror 21 to the center of the total reflection mirror 22 and the PBS mirror 21
Is set equal to the sum of the distances from the center of the lens 29 to the center of the lens 29. Therefore, the effect of the lens 28 on the light guided to the eye E1 is the same as the effect of the lens 29 on the light guided to the eye E2.

The lenses 28 and 29 enlarge the viewing angle by using the light from the PBS mirror 21 as convergent light. Therefore, when displaying the same image on the FED 20, the image display device 6 can provide a larger image than the image display device 2. Conversely, when the images to be provided have the same size, the image displayed on the FED 20 can be reduced to display a wide range, and the device can provide an image with a wider field of view. When providing an image of the same size and the same field of view as the image display device 2, the eyepiece 2
The magnification of 6, 27 can be reduced, and PBS mirror 2
3. The total reflection mirror 24, the quarter-wave plate 24a, and the total reflection mirror 25 can be made smaller, and the image display device 6 can be made smaller.

The distance from the PBS mirror 21 to the PBS mirror 23 and the total reflection mirror 25 is defined by the distance between the observer's eyes E1 and E2, and between the PBS mirror 21 and the PBS mirror 23 and between the PBS mirror 21 and the total reflection mirror. 25
There is space between them. Therefore, here the lens 28,
The arrangement of 29 has no influence on the positions of the PBS mirror 23 and the total reflection mirror 25 at all. Therefore, by disposing the lenses 28 and 29, there is no possibility that the image display device 6 is enlarged.

[0076]

According to the image display device of the present invention, an element for splitting the image light from the display element and an element for guiding the split light to the first and second eyepiece optical systems with the same optical path length. Can be all mirrors. For this reason, it becomes a lightweight device. In addition, since the components are arranged in a state close to symmetry, the weight balance is good. Further, components other than the first, third and fifth reflecting elements whose positions are defined by the distance between the left and right eyes, and the first and second eyepiece optical systems can be arranged close to each other. Therefore, it becomes a small device. Therefore, the image display device is suitable for a form worn on the head or held by hand.

In particular, the first and third reflecting elements are constituted by polarization splitting films, and one between the first and second reflecting elements and between the third and fourth reflecting elements. In an image display device provided with a 波長 wavelength plate, all image light of the display element can be guided to the eyes of the observer, and a bright image can be provided.

Further, in a configuration in which a lens for expanding the viewing angle is provided between the first reflecting element and the third reflecting element and between the first reflecting element and the fifth reflecting element, the eyepiece optics is provided. A wide-field image can be provided without increasing the magnification of the system. By making the eyepiece optical system low magnification,
The fifth and fifth reflecting elements can be downsized, and the whole image display device can be further downsized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a video display device according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration of a video display device according to a second embodiment.

FIG. 3 is a diagram showing the effect of a PBS film on incident light.

FIG. 4 is a diagram illustrating an optical path of image light of the image display device according to the second embodiment and a polarization component on the optical path.

FIG. 5 is a diagram illustrating a configuration of a video display device according to a third embodiment.

FIG. 6 is a diagram illustrating a configuration of a video display device according to a fourth embodiment.

FIG. 7 is a diagram illustrating an optical path of image light and a polarization component on the optical path of the image display device according to the fourth embodiment.

FIG. 8 is a diagram illustrating a configuration of a video display device according to a fifth embodiment.

FIG. 9 is a diagram illustrating a configuration of a video display device according to a sixth embodiment.

[Explanation of symbols]

 1, 2, 3, 4, 5, 6 Image display device 10 LCD (display element) 11 Half mirror (first reflection element) 12 Total reflection mirror (second reflection element) 13 Half mirror (third reflection element) 14) Total reflection mirror (fourth reflection element) 15 Half mirror (fifth reflection element) 16 Eyepiece lens (first eyepiece optical system) 17 Eyepiece lens (second eyepiece optical system) 20 FED (display element) 21 PBS mirror (first reflection element) 22 Total reflection mirror (second reflection element) 23 PBS mirror (third reflection element) 24 Total reflection mirror (fourth reflection element) 25 Total reflection mirror (fifth reflection element) Reflective element) 26 Eyepiece (first eyepiece optical system) 27 Eyepiece (second eyepiece optical system) 22a, 24a Quarter-wave plate 26b, 27b Polarizer 28, 29 Lens 40 FED (Display element) 1 PBS mirror (first reflection element) 42 Total reflection mirror (second reflection element) 43 PBS mirror (third reflection element) 44 Total reflection mirror (fourth reflection element) 45 PBS mirror (fifth reflection) Element) 46 Total reflection concave mirror (first eyepiece optical system) 47 Total reflection concave mirror (second eyepiece optical system) 42a, 44a Quarter-wave plate 46a, 47a Quarter-wave plate 46b, 47b Polarizing plate

Claims (3)

[Claims] 1. An image display device having a display element for displaying an image and arranged in front of an observer's eyes to guide image light of the display element to both eyes of the observer, wherein light of light from the display element is provided. A semi-transmissive first reflective element disposed on the road at an angle of 45 ° with respect to a display surface of the display element, and on a light path of light from the display element transmitted through the first reflective element, A second reflection element disposed in parallel to a display surface of the display element, disposed on an optical path of light from the display element reflected by the first reflection element and inclined by 45 ° with respect to the optical path; A third transmissive third reflective element, a fourth transmissive element disposed on the optical path of the light from the first reflective element transmitted through the third reflective element and perpendicular to the optical path.
A fifth reflective element disposed in parallel with the third reflective element on an optical path of light from the second reflective element reflected by the first reflective element; A first eyepiece optical system disposed on an optical path of light from the fourth reflecting element reflected by the third reflecting element;
And the first reflected by the fifth reflecting element
A second eyepiece optical system disposed on an optical path of light from the reflecting element, a distance from the first reflecting element to the third reflecting element, and a distance between the first reflecting element and the fifth reflecting element. A video display, wherein the distance to the reflective element is equal, and the distance from the first reflective element to the second reflective element is equal to the distance from the third reflective element to the fourth reflective element. apparatus. 2. The first reflection element and the third reflection element each include a polarization separation film that transmits one of two polarization components whose polarization planes are perpendicular to each other and reflects the other. The image display according to claim 1, wherein a quarter-wave plate is provided between each of the reflective element and the second reflective element and between the third reflective element and the fourth reflective element. apparatus. 3. A lens for enlarging a viewing angle between each of the first reflection element and the third reflection element and between the first reflection element and the fifth reflection element. The video display device according to claim 1, wherein: